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noun [countable/uncountable] x pronunciation in British English /eks/
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or X x pronunciation in British English

  1. 1
    the 24th letter of the English alphabet. X is a consonant.
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  2. 2
    maths used in mathematics for showing a number whose value you do not know

    In this equation, X equals four.

  3. 3


    used instead of saying the name of a person or place when you do not know it, or when you are using them as an example

    Let us say Mr X gives a property to his son...

  4. 4
    informal a symbol used for writing a kiss, usually at the end of a letter
  5. 5
    the Roman numeral for 10
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  6. 6


    used in the past for saying that a film was not suitable for people under the age of 18
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to fall over forwards so that your face hits the ground or another surface

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the activity of exploring abandoned buildings and other manmade structures

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